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Python Program for Selection Sort

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The selection sort algorithm sorts an array by repeatedly finding the minimum element (considering ascending order) from unsorted part and putting it at the beginning. The algorithm maintains two subarrays in a given array. 

Python Program for Selection Sort

The provided Python code demonstrates the Selection Sort algorithm. Selection Sort has a time complexity of O(n^2). In each iteration, the code finds the minimum element’s index in the unsorted portion of the array and swaps it with the current index’s element. This gradually sorts the array from left to right. The example initializes an array, applies the selectionSort function to sort it, and then prints the sorted array in ascending order. The sorted array is obtained by repeatedly finding the smallest element in the unsorted portion and placing it in its correct position, resulting in an ordered array: [-202, -97, -9, -2, 0, 11, 45, 88, 747].

Python3

# Selection sort in Python
# time complexity O(n*n)
#sorting by finding min_index
def selectionSort(array, size):
    
    for ind in range(size):
        min_index = ind
 
        for j in range(ind + 1, size):
            # select the minimum element in every iteration
            if array[j] < array[min_index]:
                min_index = j
         # swapping the elements to sort the array
        (array[ind], array[min_index]) = (array[min_index], array[ind])
 
arr = [-2, 45, 0, 11, -9,88,-97,-202,747]
size = len(arr)
selectionSort(arr, size)
print('The array after sorting in Ascending Order by selection sort is:')
print(arr)

                    

Output
The array after sorting in Ascending Order by selection sort is:
[-202, -97, -9, -2, 0, 11, 45, 88, 747]

Time Complexity:  O(n2).

Auxiliary Space: O(1).

Please refer complete article on Selection Sort for more details!


Last Updated : 28 Aug, 2023
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